How to compile Go program consisting of multiple files?

I have a small program that consists of three files, all belonging to the same package (main). But when I do go build main.go the build doesn't succeed. When it was just one file (main.go), everything worked fine.

Now that I took some effort to separate the code, it looks like the compiler is unable to find the stuff that was taken out of main.go and put into these two other files (that reside in the same directory as the main.go). Which results in undefined 'type' errors.

How to compile this program that consists of multiple files?

New Way (Recommended):

Please take a look at this answer.

Old Way:

Supposing you're writing a program called myprog :

Put all your files in a directory like this

myproject/go/src/myprog/xxx.go

Then add myproject/go to GOPATH

And run

go install myprog

This way you'll be able to add other packages and programs in myproject/go/src if you want.

Reference : http://golang.org/doc/code.html

(this doc is always missed by newcomers, and often ill-understood at first. It should receive the greatest attention of the Go team IMO)

When you separate code from main.go into for example more.go, you simply pass that file to go build/go run/go install as well.

So if you previously ran

go build main.go

you now simply

go build main.go more.go

As further information:

go build --help

states:

If the arguments are a list of .go files, build treats them as a list of source files specifying a single package.

Notice that go build and go install differ from go run in that the first two state to expect package names as arguments, while the latter expects go files. However, the first two will also accept go files as go install does.

If you are wondering: build will just build the packages/files, install will produce object and binary files in your GOPATH, and run will compile and run your program.